JP2005295569A - Contactless data transmission method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a contactless data transmission method in which current consumption of a digital circuit of a transponder is greatly reduced.
The present invention relates to a method of contactless data transmission between a writing / reading device and a transponder driven by the writing / reading device, in which the writing / reading device has modulated data (f _D ) Transmit a trigger pulse in the transmission direction and / or the reception direction, the transponder generates at least a clock signal (F _TA ) upon reception of the data, and the transponder transmits the modulated data For this purpose, the synchronization signal (S _S ) transmitted by the writing / reading device is evaluated, in which case data transmission in the transmission direction and / or reception direction takes place without a synchronous system clock.
[Selection] Figure 1

Description

  The present invention relates to a method for contactless data transmission between a writing / reading device and a transponder driven by the writing / reading device.

  So-called “RFID” (Radio Frequency Identification) systems are constantly achieving further expansion. It basically consists of two parts: a “transponder” and a receiving device, ie a writing / reading device. The transponder is closely related to the object to be identified. In doing so, the receiving device receives this identification in a non-contact manner. The reader typically includes a radio frequency module (transmitter and receiver), a control unit, and a coupling element to the transponder. A transponder, which represents the original data carrier of an RFID system, generally consists of an electrical component that is a coupling element and a so-called chip.

  Outside the response range of the reader, usually transponders that do not have their own voltage supply are completely passive. The energy required to drive the transponder is transmitted to the transponder in a contactless manner by the coupling unit.

  As is common in wireless data transmission, high frequencies are also modulated by transmission data in RFID systems. Such a method is described, for example, in “Finkenzeller, Klaus; RFID Handbook, Second Edition, 2000, Karl-Hansa-Publisher, Munich, Chapters 2 and 6.” Data transmission in the transmit and receive directions is controlled by the use of a clock transmitter that provides a frequency that is greater than or equal to the data frequency. Therefore, the standard of contactless data carrier or chip card which is effective today is ISO14443 or ISO15693.

  For example, a transponder such as a so-called chip card has digital circuit components that require a clock signal. In today's processing, there are basically two different methods for generating clock signals for digital circuits. In one method, the clock can be derived directly from the electromagnetic field. In another method, the clock is generated by itself in the data carrier, for example in a semiconductor chip arranged in the data carrier.

In the two methods, the derived clock signal, or the generated clock signal, causes a large current consumption in the digital circuit, and in addition, the clock inaccuracy is an asynchronous factor between the transmitter and the transponder. It has the disadvantage of leading communication relationships.
German patent invention No. 10210037 German Patent Invention No. 10204347

  Therefore, an object of the present invention is to provide a method for contactless data transmission in which the current consumption of the digital circuit of the transponder is greatly reduced.

  This problem is solved by the procedure presented in claim 1 according to the present invention.

  In the contactless data transmission method according to the present invention, the data transmission system realizes data transmission in the phase direction without a synchronous system clock. Data exchange is basically driven by a writer / reader, where the writer / reader generates a trigger pulse for transmission or reception of data. For example, when data modulated to a high frequency carrier is transmitted to the transponder by a writer / reader, the carrier frequency for generating the clock signal is not used and the transponder generates the clock frequency from the data signal. By using a data clock with a significantly reduced frequency for generating the clock signal, it is possible to significantly reduce the digital current consumption in the transponder.

  For transmission of data to the writing / reading device by the transponder, the transponder evaluates the synchronization signal transmitted by the writing / reading device without the use of a digital clock.

  Further embodiments provide that the edges of the digital signal are used for clock generation. When an edge is detected in the digital signal, the edge is transferred to the integrated circuit in the transponder as an edge of the clock signal. At the time of transmission, no clock is generated because the data signal is not modulated onto the carrier. This leads to the fact that the integrated circuit in the transponder is not clocked at this point, and thus does not cause current consumption.

  In an advantageous manner, the clock signal can be generated such that a rising or falling edge of the data signal is evaluated as a clock edge change and transmitted to the circuit. As a result, the generated clock signal is halved and current consumption due to the rising edge or falling edge of the data signal is caused in the circuit of the transponder.

  Particularly advantageously, the transponder encodes or decodes the data with the aid of an analog time base when transmitting or receiving the data. It is done simply by evaluating the pulse duration received between the transmitted data signals. The advantage here is that the current consumption of the transponder circuit is reduced during data transmission or reception since the digital circuit is not actively clocked.

  Further advantageous embodiments are given in the dependent claims.

In one aspect of the present invention, a method of contactless data transmission between a writing / reading device and a transponder driven by the writing / reading device is provided. In the method, the writing / reading device transmits trigger pulses in the transmission direction and / or the reception direction for notification of transmission of the modulation data (f _D ). When receiving data, the transponder generates at least a clock signal (F _TA ) and evaluates a synchronization signal (S _S ) transmitted by the writing / reading device for transmitting modulated data, in which case Data transmission in the direction and / or reception direction takes place without a synchronous system clock.

Here, preferably, the clock signal (F _TA ) is generated from the clock frequency of the transmission data signal (f _D ).

Preferably, the rising edge or falling edge of the data signal (f _D ) is used for generating the clock signal. Alternatively, the rising edge or falling edge of the data signal (f _D ) is used to change the clock edge for generating the clock signal (F _TA ). Further, the rising edge or falling edge of the transmission modulated data signal (f _D ) corresponds to the length of the pulse continuation (Impulsdauer) of the data signal (f _D ) in the transponder, and the analog time constant (Z _K ). To start.

Further, preferably, after the lapse of the analog time constant (Z _K ), it is evaluated whether or not the edge of the pulse of the data signal has been changed.

More preferably, the transponder initiates an analog time constant (Z _K ) for transmission to the data writing / reading device in the presence of the rising edge of the synchronization signal.

  In the following, the present invention will be described with reference to the drawings.

In FIG. 1, a clock signal generated through a transponder and generated from a data signal is shown. On the time axis t, the transmit and receive directions with respect to the reading station, spectrum changes of the high frequency of the carrier signal fT, which is modulated by the low frequency data signal f _D is shown. First, the carrier wave signal f _T oscillates between the two signal levels 1 with an amplitude _AT . At time t1, the modulation variation 2, to take a signal level 3 transmitting signal f _T is increased from the time t1, it is present. In a first modulation variation (Modulationsschwingung) 2 of the end of the time t2, the signal level 3 of the carrier signal _{f T} again, back to the first signal level 1.

Transponder, for receiving a data reading station transmits, to sample the modulated data signal f _D, exactly when the modulation change is present, generates a clock signal f _TA indicated below the time axis t To do. At that time, the length 4 of the generated clock signal corresponds to the length of the pulse of the data signal f _D in the period t1 to t2. In a specific embodiment, further time intervals t3 to t4, t5 to t6, and t7 to t8 are shown, which clearly indicate that a clock pulse 4 corresponding to each received data pulse is generated.

In FIG. 2, the progress of the analog time constant is shown depending on the pulse of the data signal when the data signal is received by the transponder. The encoded data signal S _D and the time-based start and stop incorporated in the transponder depending on its edge change are shown up and down. The modulation variation received by the transponder is triggered by the transponder, so that from time t1, an edge change of the modulated data signal _SD is confirmed. The edge change at the same time, the transponder initiates an analog time constant Z _K. In that case, the transponder, after a lapse of the analog time constant Z _K, wherein the sample to again in time t2, the digital signal S _D to assess whether happened further level change. At time t3, finally, the level change of the digital signal S _D is performed, as a result, additional time constant Z _K is started. At that time, the state of the level is evaluated until the next level change. In this case, the data signal has a level of value “1” until time t3, so that the transponder clocks its internal circuit within that period from time t3 to time tx when a new level change occurs. Read or decode data.

In FIG. 3, the time constant started in the transponder is shown as a function of the pulse of the synchronization signal for the transmission of the data signal. To transmit the data via the transponder, the reader transmits a sync signal S _S. In this embodiment, the transponder to transmit data, at time t1, which means the falling edge of the sync pulse 5, to start the analog time constant Z _K, while the analog time constant Z _K, reads data Send to device.

  The method according to the present invention does not constantly introduce the clock from the carrier frequency or energy carrier, but only at the point in time when the data signal is transmitted, so that significant current savings are achieved when transmitting or receiving data. Enable.

Fig. 2 shows a clock signal generated from the spectral course of a modulated data signal. Depending on the pulse of the data signal transmitted to the transponder, it shows the course of the analog time constant started in the transponder. The course of the analog time constant started in the transponder, depending on the pulse of the synchronization signal for the transmission of the data signal, is shown.

Explanation of symbols

1 Signal level 2 Modulation fluctuation 3 Signal level 4 Clock pulse 5 Sync pulse

Claims (7)

A method of contactless data transmission between a writing / reading device and a transponder driven by the writing / reading device, comprising:
The writing / reading device transmits a trigger pulse in a transmission direction and / or a reception direction for notification of transmission of modulated data (f _D ),
The transponder generates at least a clock signal (F _TA ) when receiving data;
The transponder evaluates the synchronization signal (S _S ) transmitted by the writing / reading device for the transmission of modulated data, in which case the transmission of data in the transmission direction and / or the reception direction is without a synchronous system clock Done in the way. The method according to claim 1, characterized in that the clock signal (F _TA ) is generated from the clock frequency of the transmission data signal (f _D ). Rising edge or falling edge of the data signal (f _D) is characterized in that it is used for the generation of the clock signal (F _TA), The method of claim 1. Method according to claim 1, characterized in that the rising or falling edge of the data signal (f _D ) is used for clock edge modification for the generation of the clock signal (F _TA ). . The rising edge or falling edge of the transmission modulated data signal (f _D ) starts an analog time constant (Z _K ) in the transponder corresponding to the pulse duration of the data signal (f _D ). The method according to claim 1, wherein: After it said lapse of analog time constant (Z _K), the evaluation of whether an edge change of the pulse of the data signal is performed, characterized in that the performed method of claim 5. The transponder initiates an analog time constant (Z _K ) for transmission of data to the writing / reading device in the presence of a rising edge of a synchronization signal. Method.

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